You need to do several things. First, get some electronic compressed gas and blow through the vents to clean out dust and dirt. Some laptops have an access port on the bottom to access the fan area for cleaning. If this doesn't help, make sure the fan is working. If you don't here it running fast as the temperature raises, it may be faulty. Go to the Dell Diagnostics when you boot anf run the complete diagnostics. If everything is OK, but you still have high temperatures, you may have a problem with poor heat transfer to the cooling system because of incorrect application of heat transfer media. This would take professional help unless you know what you are doing. If under warranty, call Dell.

i discovered this problem early and i believe it is cos of the i7 processor i my case.. it shutts down at 99C

the i7 is way to powerful to the plastic casing that keeps the heat. the fan does a good job.. but i end up have-in another "fan" behind or under my computer " in Spain when its hot outside the computer is having some troubles.. well,,,

i believe that it is faulty construction of the Inpsiron r15 line.. i have read other threads with similar problems..

i honestly get effin mad when computer just shuts ..... next laptop i will buy - when low heat processors enter the market.. or some fierce coolig systems will be installed in laptop machines..till then a medium stationary will have to be the solution..